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| author |   Will Deacon <will.deacon@arm.com> | 2018-04-26 11:34:15 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2018-04-27 09:48:44 +0200 |
| commit | fcfdfe30e324725007e9dc5814b62a4c430ea909 (patch) | |
| tree | 21ef852058607e75e1130f198abf7f958fb26d8f /include/asm-generic/atomic-long.h | |
| parent | Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost (diff) | |
| download | wireguard-linux-fcfdfe30e324725007e9dc5814b62a4c430ea909.tar.xz wireguard-linux-fcfdfe30e324725007e9dc5814b62a4c430ea909.zip | |
locking/barriers: Introduce smp_cond_load_relaxed() and atomic_cond_read_relaxed()
Whilst we currently provide smp_cond_load_acquire() and
atomic_cond_read_acquire(), there are cases where the ACQUIRE semantics are
not required because of a subsequent fence or release operation once the
conditional loop has exited.
This patch adds relaxed versions of the conditional spinning primitives
to avoid unnecessary barrier overhead on architectures such as arm64.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boqun.feng@gmail.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1524738868-31318-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/asm-generic/atomic-long.h')
| -rw-r--r-- | include/asm-generic/atomic-long.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h index 34a028a7bcc5..5b2b0b5ea06d 100644 --- a/include/asm-generic/atomic-long.h +++ b/include/asm-generic/atomic-long.h @@ -244,6 +244,8 @@ static inline long atomic_long_add_unless(atomic_long_t *l, long a, long u) #define atomic_long_inc_not_zero(l) \ ATOMIC_LONG_PFX(_inc_not_zero)((ATOMIC_LONG_PFX(_t) *)(l)) +#define atomic_long_cond_read_relaxed(v, c) \ + ATOMIC_LONG_PFX(_cond_read_relaxed)((ATOMIC_LONG_PFX(_t) *)(v), (c)) #define atomic_long_cond_read_acquire(v, c) \ ATOMIC_LONG_PFX(_cond_read_acquire)((ATOMIC_LONG_PFX(_t) *)(v), (c)) |